<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title></title>
	<style type="text/css">
		*{
			padding: 0;
			margin: 0;
		}
		.father{
			width: 270px;
			height: 270px;
			background-color: blue;
			padding-top: 30px;
			padding-left: 30px;
			/*border: 1px solid red;*/
		}
		.xiongda{
			width: 100px;
			height: 100px;
			background-color: orange;
			/*margin-left: 30px;
			margin-top: 30px;*/
		}
	</style>
</head>
<body>
	<!-- 因为父亲没有border，那么儿子margin实际上踹的是“流” 踹的是行
	所以父亲就掉下来
	 -->
	<div class="father">
		<div class="xiongda">
			
		</div>
	</div>
</body>
</html>